Conventional lathe turrets are designed with a plurality of tool holder slots capable of receiving tool holders needed to perform a variety of metal working operations such as turning, shaping, grooving and threading. When the lathe is set up with proper tools, it can be programmed to perform a variety of metal working operations in a predefined sequence without human intervention between metal working operations to change tools.
The tool holders used in connection with a lathe turret generally include a support bar which is mounted in the tool holder slot in side-by-side relationship with a large external wedge. The wedge includes an inclined surface that engages one corner of the support bar. A screw extends through the wedge into a threaded opening in the bottom of the tool holder slot. When the screw is tightened, the inclined surface of the wedge exerts a downward and sideward force to the support bar effectively wedging the tool holder into the tool holder slot.
Prior art tool holders and the clamping mechanisms used with lathe turrets have numerous disadvantages. Because the prior art tool holder is assymmetrically disposed in the tool holder slot, the tool holder is capable of receiving only right-handed or left-handed cutting units, but not both. Further, the external wedge used for clamping the tool holder into the tool holder slot consumes so much space that it has not previously been possible to incorporate quick-change receptacles into tool holders used in connection with lathe turrets.
An additional problem encountered with prior art lathe turret tool holders is that in some instances the critical x-dimension programming point was not consistent with the original tooling. Thus, there was always a need to reprogram current productions parts when converting from the original tooling to replacement tooling.